Carburetor



Oct. 17, 1967 R. w. SUTTON 3,347,536

CARBURETOR Filed Aug. 5, 1966 4 Sheets-Sheet 2 E? a q 34 i 5 b FIG. 2

80 92 F I G. 5 INVENTOR.

ROBERT W-SUTTON BYXMIZW ATTORNEY R. W. SUTTON Oct. 17, 1967 CARBURETOR 4 Sheets-Sheet 5 Filed Aug. 5, 1966 FIG. 7

IN VENT OR. ROBERT W. SUT TON BY gm/m ATTORNEY Oct. 17, 1967 R. w. SUTTON 3,347,536

CARBURETOR 4 Sheets-Sheet 4 Filed Aug. 5, 1966 IN VEN TORY.

ROBERT w. SUTTON BYg-wvl ATTORNEY United States Patent 3,347,536 CARBURETOR Robert W. Sutton, Grosse Pointe Farms, Mich., assignor to The Bendix Corporation, a corporation of Delaware Filed Aug. 5, 1966, Ser. No. 570,499 7 Claims. (Cl. 261-34) ABSTRAUT OF THE DISCLOSURE A float type carburetor for an internal combustion engine having a throttle and an airfoil bar disposed in the induction passage posterior to the throttle, and a main fuel conduit connecting the main fuel bowl with the fuel passage in the airfoil bar. A metering jet is disposed in the main fuel conduit and a valve controlled by the movement of the throttle varies the flow through the passage in accordance with throttle position and air flow in the induction passage.

In the conventional float type carburetors for aircraft, the throttle is on the manifold side of the main fuel jet and in the operation of these carburetors, under certain conditions, severe icing occurs on or at the throttle, oc-

casionally sufficient to kill the engine while the craft is in flight. Various attempts have been made to overcome this condition by placing the main fuel discharged jet on the engine side of the throttle to eliminate the effect of the icing phenomenon, which is most prevalent in humid, moderately low temperature conditions, and while the engine is operating at idling or part throttle. Under these conditions, the moist air is cooled rapidly at the throttle by the vaporization of the fuel on or near the throttle, and by the expansion of the air and fuel mixture result' ing from the relatively high drop in pressure across the throttle. Various attempts have been made in the past to overcome the foregoing conditions by placing the main fuel discharge jet on the engine side of the throttle, thus eliminating the cooling effect of the fuel on the throttle. However, these attempts have generally been unsuccessful, in that the effect of the high mainifold vacuum on the engine side of the throttle while the throttle is in closed or part throttle position, prevents or interferes with proper metering of the fuel with a conventional venturi, and has required the use of one or more relatively complicated metering valves in the main jet system to regulate the fuel flow in accordance with air flow rather than manifold vacuum. Further, the air flowing in the induction passage past the partly opening throttle has been deflected to one side of the passage and hence has interfered with proper metering and distribution of the fuel with the use of the conventional venturi and main fuel nozzle. It is therefore one of the principal objects of the present invention to provide a float type anterior throttle carburetor which is free of idle freeze and other carburetor icing conditions, yet which effectively meters the fuel in accordance with air flow without adverse interference of manifold vacuum on the metering characteristics of the carburetor.

Another object of the invention is to provide an anterior throttle carburetor of the foregoing type in which an airfoil is used for sensing the air flow at the main discharge jet and for obtaining effective distribution of fuel in the air, and which will deliver the proper amount of fuel on the engine side of the throttle throughout the entire operating range of the engines.

Still another object is to provide an anterior throttle carburetor having the main and idle jets and accelerating pump discharge nozzle on the engine side of the throttle, in which optimum atomization and distribution of the 3,347,536 Patented Oct. 17, 1967 fuel is obtained under all operating conditions and which is compact, relatively low in height and easily installed and serviced.

Further objects and advantages of the invention will become apparent from the following description and accompanying drawings, wherein:

FIGURE 1 is a side elevational view of the present carburetor;

FIGURE 2 is a top plan view of the carburetor shown in FIGURE 1;

FIGURE 3 is a vertical cross sectional view of the carburetor shown in FIGURES 1 and 2, the section being taken on line 3-3 of FIGURE 2;

FIGURE 4 is a vertical cross sectional view taken on a line at right angles to the view shown in FIGURE 3, the section being taken on line 44 of FIGURE 2;

FIGURE 5 is a vertical cross sectional view of the carburetor taken on line 55 of FIGURE 2;

FIGURE 6 is a horizontal cross sectional view taken on line 66 of FIGURE 1;

FIGURE 7 is a fragmentary cross sectional view taken on line 7-7 of FIGURE 2; and

FIGURE 8 is a fragmentary cross sectional view taken on line 88 of FIGURE 2.

Referring more specifically to the drawings, numeral 10 designates generally the present carburetor, consisting of a body 12, with upper and lower sections 14 and 16, the two sections being secured together by a plurality of screws 18 extending through outwardly extending flanges 20 and 22 on the periphery of the two sections. The two sections contain an induction passage 24, having an air inlet 26 and afuel mixture outlet 28, the carburetor shown being an up-draft carburetor. The present carburetor is designed primarily for light aircraft, but may be adapted for automotive use, and the primary novel combination, hereinafter described, may be embodied in other types of carburetors, including downdraft and horizontal-draft carburetor induction passages.

A throttle 30 is mounted in the induction passage near the inlet thereof and the shaft is journalled in the side walls of lower section 16 and is operated by a linkage (not shown) connected to throttle lever 34 secured to one end of throttle shaft 32 by a nut 36 threaded onto the end of the shaft. The shaft forms a part of a valve structure which regulates the air flow to the fuel jets,'as will be more fully described hereinafter.

Mounted in the induction passage on the engine side of the throttle valve is an airfoil bar 40 containing the main fuel discharge jets 42 and 44 on opposite sides thereof and being held in place in the induction passage by a ring-like support member 46, seated in the wall of upper section 14. The bar extends diametrically across the induction passage and has an enlarged portion 48 on the air inlet side tapering to a relatively small or thin portion 50 on the outlet side. The carburetor is connected to an intake manifold by bolts extending through a flange 52 around the upper edge of section 14 and discharges fuelair mixture upwardly into the manifold. The air passing through the carburetor from inlet 26 and past throttle valve 30 and airfoil bar 40 is mixed with fuel from the two jets and the mixture is thence discharged through outlet 28 into the intake manifold for delivery to the engine cylinders.

The present carburetor is the float type, having a fuel chamber 60 in which is disposed a float 62 connected by a lever 66 pivoted on a pin 68 and contacting a fuel inlet valve 70 for controlling the flow of fuel from passage 72 through valve sleeve 74 to chamber 60. Passage 72 is connected by a fuel line to a fuel tank (not shown). The main discharge jets 42 and 44 are connected with the fuel chamber by passage 80, metering orifice 82 controlled by mechanically operated metering valve 84, and passages 86.

and 88, the latter passage being connected to jets 42 and 44 by transverse passages 90 and 92, respectively, in airfoil bar .40. The mechanical metering valve 84 is controlled by the operation of the throttle 30 through a linkage 93 consisting of levers 94and 95 connected at one end to stem 96 of the valve and at the other end to a lever 98 mounted on and secured to throttle shaft 32, lever 98 being operated along with the throttle valve by lever 34. As the throttle valve is opened, lever 94 lifts stem 96 and valve 84 to regulate the fuel flowing from the fuel chamber 60 through passage 80 to passages 86 and 88 to the discharge jets in bar 40. When the throttle valve is closed, the enlarged portion 100 seats on the jet 82 and closes the orifice and prevents fuel from flowing to the engine under the influence of the high vacuum created upon the closing of the throttle while theengine is running.

The idle system consistsof an idle tube 110 connected at its lower end to passage 80 and at its upper end to passageSS, and delivers fuelfrorn the fuel bowl to jets 42 and 44 while the throttle is in substantially closed position. One source of air for mixing with the idle fuel is supplied through passages 112, 114 and 116, the latter passage being connected to passage 88 delivering air for mixing with the idle fuel in passage 88 to form a fuelair emulsion which is discharged through jets 42 and 44. The air to the idle system in passages 112, 114 and 116 is controlled by a valve 120 disposed in and forming a part of the throttle shaft, and passage 122, which is subjected to impact air, as seen in FIGURE 8, connects the valve and hence passage 112 and passage 88 with the air inlet pressure. The air flow to the idle system may be regulated manually by adjustable valve 123. In order to prevent flow of fuel through the idle system when the engine is turned off but rotating, an idle shut-off is provided, consisting of a valve 124 controlled by stem 126 and lever 128.

While thethrottle is in partly closed position with the engine operating, a relatively high vacuum is normally present in the induction passage around airfoil bar 40, and this vacuum is transmitted through the jets42 and. 44 into passage 88. During this time, the idle or main jet fuel is mixed with additional air from impact air passage 130,.

passing through chamber 132 into the airfoil bar, where it is mixed with either the idle or main jet fuel in passage 88 at or near passages 90 and 92 before being discharged through jets 42 and 44. A valve 134 controls the flow of air through passage 130 and chamber132, the valve being controlled by a vacuum responsive piston 136in cylinder 138. The cylinder is connected to the induction passage by passages 140 and 142, and a spring 144 reacting between; a collar 146 on cylinder 138 and valve 134 urges the valve to closed position. The vacuum piston 136 holds the valve open in opposition to spring 144 when the throttle valve is in closed or partly closed position and the vacuum in the induction passage on the engine side of the valve is relatively high. When the throttle valve is moved to full throttle or 'nearly full throttle position, and vacuum in the induction passage is relatively low, and hence is insuflicient to retain valve 134 open. This decreases the fiow of air to the main discharge jets, and hence increases the richness of the mixture of the fuel delivered to the induction passage, performing, in effect, the function of an economizer or power enrichment systern.

An accelerating pump generally indicated by numeral 150 delivers fuel to the induction passage in outlet 28 when the throttle valve is moved toward open position. The pump consists of a cylinder 151, a piston 152, and a stem 154, the stern being connected. to the throttle valve by suitable linkage (not shown). As the piston isurged upwardly as the throttle is closed, fuel is drawn from fuel chamber 60 through valve 156 and passages 158 and 160 into cylinder 162 beneath the piston. As the piston is moved downwardly upon the opening of the throttle, the fuel is discharged through passage 164 and valve 166 to discharge nozzle 168-. A spring-loaded, lost-motion connection, indicated by numeral 169, permits rapid and normal operation without interference from the pump. In order to break the manifold vacuum effect upon the accelerating pump, the upper end of passage 164 is connected to the carburetor inlet 26 by a passage 170 and chamber 172, and in order to prevent fuel from being ejected through this passage when the accelerating pump is operated, a check valve 174 is placed in chamber 172.

The check valve includes a plate 176 which seats on both its upper and lower sides, i.e., seats onthe upper seat when the accelerating pump is discharging to prevent the outflow of fuel through the inlet air passage, and seats on thelower seat to permit air to bleed into the induction passage when the accelerating pump is not operating. An

additional valve 180 seats on valve seat 182 to closev passage 164 when the piston 152 is moving upwardly, as

through passage idle tube 110, passage 88 and fuel nozzles 42 and 44. Impact air from entrance 26 is supplied to the-idle system-through passages 122, ,112 and 116, and this air is controlled by the valve rin the throttle shaft. Additional impact airfrom the air inlet is supplied through passage and chamber 132, when valve 134 is held open by the high manifold vacuum' transmitted to cylinder 138. As the throttle is opened,.the main metering jet 82 is opened by the lifting of valve 84 from .its seat, and the fuel is thereafter controlled by meteringvalve 84 in response to variations in throttle position. Fuel passes through jet 82 into passages 86 and 88 and is discharged through jets 42 and 44. While the manifold vacuum is relatively high during part throttle operation, the valve 134 is held in open positionand the air is supplied throughpassage 130 and chamber 132 to passage 88 and is mixed with the fuel therein before it is discharged by the two jets. As the throttle is opened further or the engine placed under additional load, the manifod vacuum decreases, permitting valve 134 to close,

thus increasing the richness of the mixture discharged by the main discharge jets 42 and 44. I

The main jet being disposed in the airfoil bar 40 on the engine side of the throttle produces effective distribution and atomization ofthe fuel in the air flowing through the induction passage. The relationship of the bar to the throttle position, both in distance and in angle, avoids any icing and maldistribution of the air in the induction passage around the main discharge jets. During acceleration, the pump is operated by mechanical linkage with the throttle, thereby discharging fuel through passage 164 and valves 180 and 176, and thence through jet 168 into the induction passagenear outlet 28 of the carburetor. When the accelerating pump is not in operation, a small amount of air is bled into the induction passage through impact air passage and valve 174, thus effectively preventing the manifold vacuum from influencing the operation of the accelerating pump either during acceleration or at any other time during the operation of the engine.

When the throttle valve is moved towardclosed position, the manifold vacuum transmitted to the induction passage increases, again opening valve 134 for admitting While only the preferred embodiment of the present invention has been described in detail herein, various changes and modifications may be made without departing from the scope of the invention.

I claim:

1. In a carburetor having a fuel bowl and an induction passage with an air inlet and a mixture outlet: a throttle in said induction passage, an airfoil bar disposed in said induction passage posterior to said throttle and having a fuel passage in one end and an air passage in the other end and a discharge jet on each side near the center of the bar connected to said fuel and air passages, a main fuel conduit connecting said bowl with said fuel passage, :1 metering jet in said conduit, a valve for controlling the fuel flow through said metering jet, a linkage connecting said valve with said throttle for regulating the flow of fuel in accordance with throttle position, a passage for impact air connecting the passage in said bar with the induction passage on the air intake side of the throttle, and a valve responsive to manifold vacuum in said impact air passage for closing said air passage when the throttle is in substantially wide open position.

2. A carburetor as defined in claim 1, in which said throttle is mounted on a throttle shaft pivoted in the Wall of the carburetor, and the axis of said airfoil bar is disposed in transverse relationship to the axis of said throttle shaft.

3. A carburetor as defined in claim 2, in Which said airfoil bar is spaced sufliciently far from said throttle to obtain substantially uniform distribution of air around and along the airfoil bar.

4. A carburetor as defined in claim 1, in which an idle fuel conduit communicates with the main fuel passage anterior and posterior to said metering jet, and a passage is connected to said fuel passage for supplying impact air for forming a mixture with the idle fuel.

5. A carburetor as defined in claim 4, in which a valve is disposed in said impact air passage and is controlled by the movement of the throttle valve to open said passage to the fiow of said impact air when said throttle valve is moved to closed position.

6. A carburetor as defined in claim 1, in which is included an accelerating pump system, said system having a pump, passages connecting the pump to the fuel bowl and to the induction passage on the posterior side on said throttle, a passage for impact air connected to the last mentioned passage, and a valve for closing said impact air passage when said pump is operating and for admitting air into the induction passage when said pump is inoperative.

7. A carburetor as defined in claim 1, in which is incorporated an accelerating pump system having passages connecting the pump to the fuel bowl and to the induction passage on the posterior side of said throttle, a passage for impact air connected to the last mentioned passage, and a valve for closing said impact air passage when said pump is operating and for admitting air into the induction passage when said pump is inoperative.

References Cited UNITED STATES PATENTS 2,056,615 10/1936 Moore 261- 2,223,381 12/1940 Mock.

2,237,922 4/1941 Beck 261-50 2,269,949 1/1942 Mallory 26'l50 2,277,930 3/1942 Mock et al.

2,406,114 8/1946 Sloan et al. 261--34 2,849,216 8/1958 Perotti et al 26150 X 3,057,607 10/1962 Kuhn et al. 261-78 3,147,320 9/1964 Tubb 26150 3,215,413 11/1965 Szwargulski et al 26141 HARRY B. THORNTON, Primary Examiner. TIM R. MILES, Examiner. 

1. IN A CARBURETOR HAVING A FUEL BOWL AND AN INDUCTION PASSAGE WITH AN AIR INLET AND A MIXTURE OUTLET: A THROTTLE IN SAID INDUCTION PASSAGE, AN AIRFOIL BAR DISPOSED IN SAID INDUCTION PASSAGE POSTERIOR TO SAID THROTTLE AND HAVING A FUEL PASSAGE IN ONE END AND AN AIR PASSAGE IN THE OTHER END AND A DISCHARGE JET ON EACH SIDE NEAR THE CENTER OF THE BAR CONNECTED TO SAID FUEL AND AIR PASSAGES, A MAIN FUEL CONDUIT CONNECTING SAID BOWL WITH SAID FUEL PASSAGE, A METERING JET IN SAID CONDUIT, A VALVE FOR CONTROLLING THE FUEL FLOW THROUGH SAID METERING JET, A LINKAGE CONNECTING SAID VALVE WITH SAID THROTTLE FOR REGULATING THE FLOW OF FUEL IN ACCORDANCE WITH THROTTLE POSITION, A PASSAGE FOR IMPACT AIR CONNECTING THE PASSAGE IN SAID BAR WITH THE INDUCTION PASSAGE ON THE AIR INTAKE SIDE OF THE THROTTLE, AND A VALVE RESPONSIVE TO MANIFOLD VACUUM IN SAID IMPACT AIR PASSAGE FOR CLOSING SAID AIR PASSAGE WHEN THE THROTTLE IS IN SUBSTANTIALLY WIDE OPEN POSITION. 